Recently, demands for various display devices are increasing, along with the rapid development of communication technology. There are several kinds of display devices commonly used, including: cathode-ray tube (CRT) display, liquid crystal display (LCD), plasma display panel (PDP), electro luminenscence display (ELD), vacuum fluorescence display (VFD), and the like. LCD devices, due to their characteristics like light, thin, small size, low power consumption, less radiation, and the like, are widely used in various data processing devices, such as television, laptop, mobile phone, personal data assistant, and so on.
A LCD device may mainly include following components. A substrate is provided, in which a backlight source is disposed. A pixel electrode and a thin film transistor (TFT) array are disposed on the substrate. The TFT array is electrically coupled to the pixel electrode and is used to control the electric potential of the pixel electrode. The LCD device further includes a color filter plate, and a liquid crystal layer between the pixel electrode and the color filter plate. On a surface of the color filter plate which is facing the liquid crystal layer, there is provided with a common electrode layer. Electric potential is applied to the pixel electrode through the TFT array, such that an electric potential difference exists between the common electrode layer and the pixel electrode. Liquid crystal molecules in the liquid crystal layer may deflect to certain angles depending on magnitudes of the electric potential difference. Therefore, the amount of light, which is emitted from the backlight source, passes through the liquid crystal layer and arrives at the color filter plate, can be controllable. The backlight used in the LCD device is white light. Since only polarized light can pass through the liquid crystal layer, nearly 50% of the light may be wasted. When the light is passing through the color filter plate, the upmost usage of the light may be only 33%. As a result, light usage in conventional LCD devices may be relatively low. Further, conventional LCD devices may have other drawbacks, such as narrow view angle coverage, complex construction, high cost, and the like.
Along with the development of micro-electromechanical system (MEMS) technology, MEMS light valves are tending to be used in display devices to replace liquid crystal layers. Luminousness of backlight may be controlled by using the MEMS light valves. TFT-MEMS can be integrated into current TFT-LCD panel micro manufacturing technologies. Using the MEMS, which have the advantages of high speed and high efficiency, to replace liquid crystal, there is no longer need for polaroids, color filter plates or indium tin oxide (ITO) electrodes. Therefore, light usage may be greatly increased, power consumption and manufacturing costs may be reduced.
A display device having a MEMS light valve is disclosed in U.S. Pat. No. 7,271,945B2 which is published on Sep. 18, 2007. However, the MEMS light valve has disadvantages like complex structure and low sensitivity.